Because, Bretons are not showing even a liitle bit of regret over the banning of Talos worship. The Redguards had every reason to dispute the WGC, because the Imperial handed over half of their land. Besides I still see no evidnce in game that suggests Thalmors are demising anythingelse besides the fall of the empire and policing of Talos worship.

I don't even think the real empire of Rome ever truly "crumbled". Rome, the locale, crumbled, and Byzantium dwindled at a slower pace.. but where Rome fell, the Franks basically replaced them. And being formerly influenced by Romans, they took a lot of cues from them. Coupled with different religious leanings, Charlemagne became the new "Caesar" of the Holy Roman Empire. And then Western Europe became a game of "bobbleheads". Knock one expression of the Empire out, and another would pop up. Hell, even the proper name "Caesar" became equivalent to the word "leader or emperor" in these settings. "Kaiser". They all wanted to reenact the Roman Empire, basically.

There are a lot more nuances than this, but this is just an internet post, and I don't want to bore everyone. Point being though, if one were to borrow ideas from history for this game, it'd turn out to be some scenario where Nords resembled Franks or something.